Posted
by
kdawson
on Thursday March 15, 2007 @08:10AM
from the string-net-liquid dept.

Matthew Sparkes writes "In theory, quantum computers can be superior to classical computers for some kinds of problems; in practice their building blocks, qubits, are extremely fragile. Even a slight knock can destroy information. A radical solution to this problem was proposed in the 80's — instead of storing qubits in properties of particles, such as an electron's spin, it was suggested that qubits could be encoded into properties shared by the whole material, and so would be harder to disrupt. Unfortunately, no material with the needed properties existed. Scientists now think they have made a material in the lab, thought to be an example of a new state of matter, that might do the trick. It's an ultra-purified form of a mineral, herbertsmithite, first discovered in Chile in 1972. Its electrons are arranged in a triangular lattice. Researchers say it could become the silicon of the quantum computing era."

Surprisingly enough not Herbert Smith. TFA states that the material was named after a man the discovering geologists admired greatly.
On another note, this material seems really interesting and I hope its unique properties can be applied usefully.

Unfortunately, while TFA is descriptive and informative, it reads more like a PR than a scientific paper. It sounds like everything still needs to be verified. The headline is certainly misleading, as no experiments of any sort have been done to prove that they can do any of the manipulations that are required to advance quantum computing.

This is merely the very very early stages of basic research. Very interesting none the less.

But suspensions and the like are mixtures with sometimes odd behavior. Toothpaste and liquid body armor are two with oddball properties. Basic glass is another odd material, a homogeneous super-cooled liquid that mostly acts like a solid. But they all fall within the "normal" states.

Plasma and B-E condensates have both been created in the lab. It's interesting to see a natural new state appearing on the planet.

The implication that the information is distributed like that in an optical hologram is very interesting, and doubly difficult to get my head around...

But the fact remains that if you damage/disturb a holographic store you lose some information, even if that loss is spread over a large set of information. Maybe the ECC (error-correcting-code) technology being used in new small-geometry silicon CPUs could help if it can be done 'quantum-ly'.

This hardly seems to be a new kind of matter (i.e., matter, dark matter, anti-matter), or even a new phase of matter (solid, liquid, gas, [plasma?]). The article means it's a new phase, as it talks between the difference between solid and liquid. However, it mentions electrons as the determining factor, where it's actually nuclei. Heck, in solid metal, atoms have a lattice structure, but valence electrons flow freely from one to another, which is what makes metals such good conductors. The only thing remarkable about this compound is that it is supposedly arranged in a new space group.

In the traditional Landau paradigm, phases of matter arise as broken symmetries of the Hamiltonian, with different phases corresponding to different symmetries and described by a "local order parameter" (e.g. magnetization).

With the advent of developments in high-temperature superconductivity and the quantum Hall effect, new phases were found that exist completely outside the Landau paradigm: topological order [wikipedia.org], in which there is no local symmetry, yet the topology of the system can globally distinguish one phase from another.

Excitations of these systems with topological order were once thought to be necessarily "gapped", that is, the quasiparticle excitations have an effective mass. However, Wen has proposed a more general notion of "quantum order", in which gapless (massless) quasiparticles, analogous to photons or other gauge vector bosons, can appear.

The mechanism by which this occurs, in Wen's paradigm, is through "string net condensation". In quantum field theory, from the work of Polyakov and others, it is possible to think of the field lines connecting particles as "strings", with the particles residing at the endpoints of the strings. The fields are gauge fields, so the "stringy" field lines correspond to the massless gauge bosons, as opposed to the massive matter particles that serve as the string endpoints. Wen's quantum order has excitations in a spin lattice correspond effectively to strings (massless "force field" quasiparticles), which are open, i.e., have endpoints (massive "matter" quasiparticles).

There are actually strong analogies between these ideas and actual string theory (as noted by my reference to Polyakov's work). In fact, Wen did his Ph.D. in string theory under Edward Witten before switching to condensed matter.

The work [arxiv.org] discussed in this story is an experimental demonstration of a system with gapless excitations that do not obey Landau's local order paradigm, and thus relate to Wen's work on quantum order. (I am fuzzy on the details so I don't know to what extent this work is a confirmation of Wen's theories. I also don't know how novel gapless excitations are without symmetry breaking.)

You can read more about this from his work [arxiv.org], such as this [arxiv.org]. Wen has even proposed that perhaps the actual photons and electrons we think are real are really just quasiparticle excitations arising from a low energy (large scale) effective field theory of some underlying submicroscopic lattice that we can't see — see here [arxiv.org]: he can recover many (but not all) of the aspects of the particle physics this way, and argues that it unifies light and matter (since open strings always have endpoints). I think he has problems with chiral fermions, IIRC. The big stumbling block is of course gravity, although he has made efforts in that direction too (here [arxiv.org]). He has written a graduate textbook [mit.edu] on these ideas; he also has some talks up on his web page [mit.edu].

Excitations of these systems with topological order were once thought to be necessarily "gapped", that is, the quasiparticle excitations have an effective mass. However, Wen has proposed a more general notion of "quantum order", in which gapless (massless) quasiparticles, analogous to photons or other gauge vector bosons, can appear.

One thing that immediately sprang to mind was that this might have an impact on the notions of phonons (not photons) in a crystalline lattice. Perhaps they are not quantized

In Wen's theory phonons remain quantized; his theory is fundamentally quantum in nature (his work is based on ordinary quantum spin lattices). I don't know this experiment should have anything to do with the quantization of phonons.

Wen has even proposed that perhaps the actual photons and electrons we think are real are really just quasiparticle excitations arising from a low energy (large scale) effective field theory of some underlying submicroscopic lattice that we can't see

This seems to fit well with the Discrete Universe ideas. Thanks for the links.

Herbertsmithite...[r]esearchers say it could become the silicon of the quantum computing era.

The new technology center, in the San Francisco Bay Area, formerly known as Silicon Valley has been rechristened "Herbertsmithite Valley". Stars are flocking to get the new Herbertsmithite Breast Implants (Quantum Boobies).

I've always wondered why scientists attempt to separate everything. I suppose having a small section of nature makes it easier to understand, but everything is one, you can't separate me from my environment and you can't separate light from matter.

Scientists don't attempt to separate everything. Much of modern physics has been concerned with unifying things together, in fact. A lot of that unification has been with the fundamental forces. String theory provides one way to unify the forces (e.g., electromagnetism or "light") with matter: force-carrying particles and matter particles are both vibrational modes of strings. The "string net condensation" idea is a different way to unify light and matter: forces as strings, matter as the endpoints of

"...ultra-purified form of a mineral, herbertsmithite, first discovered in Chile in 1972. Its electrons are arranged in a triangular lattice. Researchers say it could become the silicon of the quantum computing era."

This is the "silicon of the future"? If it wasn't discovered until the 1970s it doesn't sound exceedingly common...

At least we can be sure that "Dippin' Dots" will be "the ice cream of the quantum computing era."